1. Field of the Invention
The present invention relates to an image forming apparatus and, more particularly, to a recording electrode assembly used in an image forming apparatus such as a printer or a display device of a type wherein a voltage is applied between a recording electrode and a recording medium to attach image forming particles (i.e., toner) to be recording medium, and an image forming apparatus using the electrode assembly.
2. Related Background Art
Examples of such a conventional image forming method are described in U.S. Pat. Nos. 3,816,840, 3,914,771, 3,946,402, and 4,268,598. According to this image forming method, as shown in FIG. 2, conductive magnetic toner 1 is fed onto a nonmagnetic cylinder 3 in a predetermined direction by a rotary magnet 2 having opposite magnetic poles arranged alternately along its circumferential direction. The toner 1 passes through a large number of recording electrodes 4 adjacent ones of which are electrically insulated from each other. A voltage is applied between the recording electrodes 4 and a conductive layer 7 on the recording medium 5 with an insulating layer formed thereon. The toner applied with a voltage having a polarity opposite that of the voltage applied to the conductive layer 7 is attracted to the insulating layer 6 on the surface of the recording medium, thereby forming an image.
The arrangement of a recording apparatus according to the above method is very simple and provides many advantages. However, the recording apparatus presents a major disadvantage in that the recording electrodes cannot be subjected to division driving. More specifically, signal voltages must be independently applied to the recording electrodes to form an image. For this purpose, conductive wires having the same number as that of the recording electrodes must be arranged between the recording electrodes and an electrode driver so as not to interfere with toner feeding.
In a conventional apparatus of this type, the wires run along the nonmagnetic cylinder 3 and are guided along the axial direction thereof. A typical example is illustrated in FIG. 3. The recording electrodes 4 are connected to conductive wires 8 formed on a flexible printed circuit board in units of recording electrodes 4. The conductive wires 8 are axially bent and guided on the nonmagnetic cylinder 3. Another typical example of wiring is described in U.S. Pat. No. 3,879,737.
According to the method wherein the electrodes are divided into blocks and are connected in units of blocks, however, high precision of connections between the electrode blocks cannot be obtained. In addition, connections of the wire electrodes stacked and axially guided are complicated. According to still another conventional example, the recording electrodes and the electrode driver are formed integrally on the nonmagnetic cylinder 3. However, it is difficult to mount all components so as not to interfere with toner feeding on the nonmagnetic cylinder.